SECRETION. 



403 



Hence it must be concluded that the thyroid gland is a struc- 

 ture essentially connected with the metabolism of the blood and 

 tissues. In performing its functions it is a blood-agent, both directly 

 and indirectly. In the human foetus the gland-tubes, or rather 

 cylinders of epithelium, commence their secretory activity during 

 the interval from the sixth to the eighth month. In proportion to 

 the body-weight, the gland is heaviest at birth and diminishes not- 

 ably toward the end of life. Therefore the thyroid gland is in f unc- 



Fig. 146. Illustrating Nicholson's Article on Thyroid Treatment in a 



Cretin (Arch, of Fed., June, 1900). (RAYMOND.) 



A, Before treatment. B, After treatment. 



tional activity before birth, and is of special metabolic importance 

 in early extra-uterine life. Its value falls as the general vital pro- 

 cesses decrease. 



The thyroid body is one of those organs of great metabolic 

 importance, since its removal or disease is followed by general dis- 

 turbances. Experimental thyroidectomy is very much more fatal in 



